Process of plastering



Mafch 31. 1925;

' C. O.`WALPER PRocEss 'oF PLASTERING lFiled July 20, 1922 n -u c WIM.

Patented Mar. 31, LIS.

CURRY ORA wALPER, OF DETROIT, MICHIGAN,

l v PLAsT coRroRATIoN or MICHIGAN. I I

' application filed .Tary 2 To allee/10m t may concern.'

. citizen .of the Unite residing at Detroit, i

` g psum plaster h various layers-o In order to c vide a smooth and CURRY ORA `INALPER, a d States of "-"Am'erica, n the county of Wayne and State of Michigan, have invented certain new and useful Improvements in Processes of Plastering, of Whichthe following is a specification`- 1 This invention rel Be it kno-Wn that I,

ates toa system of'plasvtering particularly applicable in'providing a finishing coatv for a Wall board surface. f The primary object of my invention is provide a nishing co'at adapted for use'witli Wall boards having .a surface Icoating'of' paper or other porousmaterial.

, A still further object'of the invention is to` provide a finishing .coating `which may be rapidly applied to a porous surface to prouni continuous-operation.

The increasing cost of lathing and of labor vhas led to the provisionof manyl formsof Wall boards Aad studsV and joists metal lathing. made of various Without the use of Woodor forms of paper pulpor of aving a paper surface.A In some eases the composition boards consist of material.

oncealthe joint at the meeting e'dffes ofsuch boards variousformsvv of crack illers have been used, lthese filling compositions usuall setting mixture .of gypsum containing lglue or wood flour or other inert materials. However ythe shrinkingr and warping ofthe material of the Wall Aboards due-tol variations in moisturein the air orin the Walls is usually `suieient to cause cracks to form at the meeting edges and other strainsl such as those due to hammering or strains causedby'drying of the studs and joists will also act to produce cracking. It has therefore been deemed neces sary to apply upon the surface of such plaster boards a roughv coat of plaster, in many cases as thick as the wall 4board itself, and

- upon this rough coat a finishing or putty .i high as tifteen per coat. is putty coat commonly consists of lime with a little gypsum added and'while the percentage of gypsum may be made as cent', the'tendency on the part 'of` Workmen is. to use lessV than this quantity, since in the ordinary-manner of form finish in' 'a Single ,uch boards are commonly f paper', plaster, and other'y y consisting of some quick ERING c rnooisssor PLASTERING.

o, -1922. serial Nbxsrazsif i. preparation ofsuch mixturel aV larger quan- AssIGNoR, BY DIRECT AND srsTnivr,V oF DETROIT, MTCHTGAN,.A

tty O gypsum vusually ycauses dilli'culty in@ the application o face l i i f Gypsum ordinarily sets more rapidly tha-n is'conrenientl for the application ofl a ysurface coat if it is us ducing `the best res ished wall ,and the .reduce`the amount to avoid the' preparation -of numerous'small batches .of materiaBy increasing ,the percentage of lime, a larger amount' of Wet putty at one time Without danger of injurious setting before it can be i coat. This ordinary putty coat is not satisf the coat tothe Wall surs ultsv in the ordinary lined in a percentage pro- -tendei'icyI is therefore to applied .to the rougll 17"- 0 coat may be,.prepare d l factoryas a surface finish for paper'coat'ed plaster boards.

'moisture duri facilitate-the dioxide' and to ng its hardening process to This moisture The lime yrequires-1a-certainamount 'of' rapid absorption of carbon 4. prevent lundue shrinkage vof apted to be nailed directly to'v thel surface during setting.

is Ausually supplied by Water absorbedby the usually applied. V

In the case of plasteryboards havingv a paper surface there is not enough'moisture absorbed and 'retained to cause 'a ting of the lime and it the ordinary putty coat cannot be used satisfactorily directly upon the surface of the plaster boards coat. e i The, accompanying drawing" indicates lin transverse section :L xvallif'plaster board vcoated in accordance with this invention.

" The composition of the present inventionconsists of a mixture of gypsum fifty per cent, lime fifteen per cent to 'forty per cent and sand, Where sand is used, ten per cent,

1 though the mixture may" be usedv free .from

rough coat to which the finishing coat is proper sethas been found that I as a single unitary finishing*A of tl'ieprimary coating ,y

vcentto seventy-five per sand The preferred mixture consi-stsy of e thirty per cent If .thegypsum is as iration to the surface of the equantity of water will vary with cent, Vthe lime may a consistency adaptingjit for y' `used With. a large percentage of lime,

Y vphere,

`the degree of porosity age of gypsum will A pending paper coated boards or to of the surface of the boards, a very porous board requiring amixture containing a greater quantity of Water than Would be required by a board having a surface only slightly absorbent.

A' composition having this high percentcling very tenaciously to a paper lor other porouslsurface and While it is somewhat brittle, it has great, elasticity, permitting considerable bendingv Without cracking. A sufficient amount of commercial retarder will beused in the preparation of the mixture to prevent too rapid setting of the composition. For best results, the paper surface should be sufficiently porous to absorb a considerable amount o-f Water butshould not have enough suction to dry out the plastic mixture to an extent preventing proper Setting and' hardening of the composition. v i i f It is to be observed that Whereas in the previous composition used for the ordinary putty coat a small percentage of gypsum s t e purpose of the gypsum being. to produce -a rapid setting of the mixture sufficient to prevent injurious shrinking, but the mixture defor its ultimate hardness, upon the conversion of the colloidal hydroxide of calcium into calcium carbonate by the absorption .of carbon dioxide from the atmosin the present instance lthe primary coating dependsfor its hardness upon the high percentage of gypsum present and upon the sand When the sand is used, theI lime-together with the retarder being used only for the purpose of producing the smooth flowing mixture capable of beingapplied as a thin coating upon the surface of the boards.

After the Workman has applied la thin coating of this composition having a high percentage of gypsum to the surface of the any other suitable porous surface, there will be a certain absorption of moisture which will occur very soon after the application of the coating and .if the amount of retarder has been properly regulated the mixture Will begin to set very soon after the Workman-'has completed the necessary smoothing of the primary coat. With Wall boards of l the ordinarytype -coated with paper a layer three-sixteenths -e of an inch in thickness has been found to be suiiicient.

As soon .as `the Workman has covered the space readily reached fromhis scaffolding,

the material ii-rst applied Will have set suf(- fici'ently to receive the finishing coat. Thev primary coat should still be Wet but even ,in this condition the gypsum composition will have a considerable suction and will be Well adapted to receive the finishing coat.

The lfinishing coat Will preferably not contain as high apercentage of gypsum as is contained in the primary coat, since with a smoothly,

' quantity of obtain a surface as smooth as is. usually. desired. v By increasing the percentage of lime, a composition Which will Work much more smoothly is obtained. The-preferred percentage of. this finishing coat Will be lime sixty per cent and gypsum forty per cent, the sand being omitted. A certain amount of commercial retarder lwill be used to prevent too rapid setting yof the gypsum. .l

This finishing coatingl 'Will be applied in a very thinlayer, upon the surface of the primary coating which Will be set sufficiently to be rigid underthe pressure of -the plasterers tools,

though it will still be Wet With the moisture it contained When it Was applied. The plasterer *Will' quickly apply this "thin surface coating over the primary coating ready to receive it and by the time he has completed the spreading of the finishingcoat,y the portion irstapplied will have'lost sufficient moisture by the suction of the primary coating so thatit will be ready for the-final rubbing in with the finishing tool.

It will be seen. complete finishing to a paper Wall other suitable porous surface in what is practically a single operation, with 'a single that by this system the coating may be applied board surface or to any setting of the scaffolding. By the use of I the compositions described, only a small material Will be required as compared With the ordinary plastered surface and the resulting finish will be smooth and hard.

By this system there is provided a primary coating Which Will adhere tenaciously to a vpaper surface and which Will have great elasticity, and a finishing .surface coating Which Will adhere to the primary coating While havingl good Working qualities enabling a workman to expenditure of labor and time.

The system is economical in that it permits the production of a iinished surface coating upon a wall board foundation .With a small quantity of material rapidly applied Without the necessity of Waiting for the drying of a rough coat as in ordinary plastering. Lime in the primary coat not only makes it Work more smoothly, but also checks the corrosive action of the gypsum on the metal reinforcements used in covering the meeting produce a hard smooth and satisfactory surface with a minimumv .ico

edges ofthe boards and the'fastening means as described in my coending a lication semi No. 576,969. p a, pp

The primary coating containing a high percentage of gypsum will adhere to the paper coating of a Wall board even when it has been sized to limit the vabsorption of VWaterv by the board. The addition of sand or scoriailengthens vthe time of setting but does not prevent this adhesion.

' proper adhesion.

The primary 'coating containing gypsum in high percentages has the peculiar qluality of having great suction even While sti l Wet, after it has acquired its set. This feature makes possible the immediate use of the inishing coating with excellent results. In the preparation of this nishing coat, to secure the proper consistency for easy mix- -ing and to slake the lime, a considerablequantity of Water is used, which results in a thin mixture. This cannot be properly nished until some of the Water is removed. The suction ofthe Wet primary coating is sufficient to remove enough Water to bring the inishing coating to a consistency enabling the Workman to apply the linal troweling with ease.

I claim 1. A process of plastering which consists in applying to a porous surface an adhesive quick setting plastic gypsum composition as a primarycoating and after the primary coating has taken its setting but before it has become dry applying to the, surface therof a finishing coating of a comparatively slow setting plastic composition containing gypsum.

2. A process of plastering which consists in applying to a porous surface a plastic composition' containing gypsum in excess of fifty per cent as a primary coating and after the primary coating has taken'its set but before it has become dry applying the finishing coatingthereto consisting of a plastic composition containing less than fifty vper cent of gypsum.

3. A process of'plastering which consists in applying to a porousvsurface a plastic composition containing lime and gypsum with the gypsum in excess and after the composition has set but before it is dry applying a nishing coatingcontainin`g lime and gypsum with the lime in excess.

In testimony whereof I aiiix my signature in presence of two witnesses. l

Witnesses:

ARTHUR MINNICK, GEFA L. TERNA. 

